Ruggedized and integrated hybrid generators and related methods

ABSTRACT

Ruggedized generators can operate using both medium and heavy fuels and output at least 5 kWe of power, yet are quiet, compact in size, and reliable.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application63/161,958 filed Mar. 16, 2021 (the “'958 Application”). Thisapplication also incorporates by reference the entire disclosures setforth in the '958 Application as well as the entire disclosures setforth in U.S. Non-Provisional application Ser. No. 17/151,253 (the “'253Application”).

TECHNICAL FIELD

This disclosure relates to the field of generators, and particularly, toa generator that incorporates an inwardly opposed piston engine (OPE)that can operate using one or more fuels (e.g., Jet Propulsion (JP) 8fuel, NATO F-24 fuel, D2 fuel), for example.

INTRODUCTION

This section introduces aspects that may help facilitate a betterunderstanding of the disclosure. Accordingly, the statements of thissection are to be read in this light and are not to be understood asadmissions about what is, or what is not, prior art.

To date, it has been challenging to produce a generator that can operateusing both “medium” (gasoline) and “heavy” (diesel) fuels in order toproduce at least 5 kilowatts (kW) of power. Existing internal combustion(IC) engines that may be used as a generator have difficulty burningheavy fuels. A further challenge is to produce a small generator(weight-wise and size-wise) that is capable of using both medium andheavy fuels. Typically, small existing IC engines run at high speeds andhave very short power strokes making it difficult to efficiently operatesuch engines using heavy fuels.

Accordingly, it is desirable to provide a generator that can operateusing both medium and heavy fuels that outputs at least 5 kWe of power,yet is quiet, small in size, and reliable.

SUMMARY

The inventors describe various exemplary, inventive systems that arecompact in size and include generators capable of using both medium andheavy fuels while producing at least 5 kWe of power.

In one embodiment, an inventive compact and ruggedized system forproducing power may comprise: a first generator; a second generator; andan engine connected to the first and second generators to provide energyto the first and second generators, where the engine may comprise one ormore cylinders, where each cylinder may comprise, a long-reach sparkplug for ignition and combustion close to a center of a combustionchamber of each cylinder, a glow plug, and at least one direct injectorconfigured to inject fuel towards the glow plug and into the combustionchamber.

In such a system the first generator may output at least 5 kWe of power,and the engine may be an inwardly, opposed piston engine.

The system may further comprise a second direct injector configured toinject fuel towards into the combustion chamber and towards the sparkplug, wherein the fuel injected by the at least one injector and thesecond injector may generate tumbling fuel about a center axis of eachcylinder.

A second exemplary compact and ruggedized system for producing power maycomprise: a first generator; a second generator; and an engine connectedto the first and second generators to provide energy to the first andsecond generators, where the engine may comprise one or more cylinders,where each cylinder may comprise, at least one direct injectorconfigured to inject fuel towards a glow plug and towards a pre-chamber,the pre-chamber configured to receive at least one spark plug forigniting the fuel from the direct injector, and a glow plug for ignitingfuel from the direct injector.

Similar to before, the first generator of this system may also beconfigured to output at least 5 kWe of power, for example and the enginemay be an inwardly, opposed piston engine.

Still further, the inventors provide additional inventive compact andruggedized systems for producing power. One such additional system maycomprise: a first generator; a second generator; and an engine connectedto the first and second generators to provide energy to the first andsecond generators, the engine may comprise one or more cylinders, whereeach cylinder may comprise, a pre-chamber configured to receive a directinjector configured to inject fuel into the pre-chamber and furtherconfigured to receive at least one spark plug for igniting the fuel fromthe direct injector in the pre-chamber and creating a heated turbulentflow out of the pre-chamber and into the combustion chamber of thecylinder to ignite fuel in the combustion chamber, and a glow plug forigniting fuel from the direct injector.

Again, similar to before, the first generator of this system may also beconfigured to output at least 5 kWe of power, for example, and theengine may be an inwardly, opposed piston engine.

The inventive systems (and corresponding methods) described above arejust some of the inventive systems and methods that will be apparentfrom the discussion herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and is notlimited by the accompanying figures in which like reference numeralsindicate similar elements and in which:

FIG. 1 depicts a simplified block diagram of a system for providingpower according to one embodiment of the present disclosure.

FIG. 2 depicts a simplified block diagram of an exemplary thermalmanagement system according to one embodiment of the present disclosure.

FIG. 3 depicts an exemplary configuration of a muffler, radiator andexhaust mixer according to one embodiment of the present disclosure.

FIG. 4 depicts exemplary experimental results of sound attenuationprovided by the configuration depicted in FIG. 3 .

FIGS. 5A and 5B depict front and back views of an exemplary engine andgenerators according to one embodiment of the present disclosure.

FIGS. 6A and 6B depict an exemplary engine cylinder configurationaccording to one embodiment of the present disclosure.

FIGS. 7A to 7C depict views of an exemplary fuel delivery subsystemaccording to one embodiment of the present disclosure.

FIGS. 8 to 12 depict views of additional, exemplary engine cylinderconfigurations according to embodiments of the present disclosure.

FIGS. 13A to 13C depict different views of an exemplary adaptor that maybe used to connect one or more different components to the cylinder ofan exemplary engine according to embodiments of the present disclosure.

FIGS. 14A to 14C depict views of exemplary components of an exemplary,ruggedized enclosure according to embodiments of the present disclosure.

FIGS. 14D to 14F depict views of exemplary engine mounting structuresaccording to embodiments of the present disclosure.

FIGS. 15A to 15C depict views of a thermal transfer structure (e.g., aheat sink) according to embodiments of the present disclosure.

FIGS. 16A to 16D depict intake and exhaust valve configurationsaccording to embodiments of the present disclosure.

Specific embodiments of the present invention are disclosed below withreference to various figures and sketches. Both the description and theillustrations have been drafted with the intent to enhanceunderstanding. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements, andwell-known elements that are beneficial or even necessary to acommercially successful implementation may not be depicted so that aless obstructed and a more clear presentation of embodiments may beachieved.

Simplicity and clarity in both illustration and description are soughtto effectively enable a person of skill in the art to make, use, andbest practice the present invention in view of what is already known inthe art. One of skill in the art will appreciate that variousmodifications and changes may be made to the specific embodimentsdescribed below without departing from the spirit and scope of thepresent invention. Thus, the specification and drawings are to beregarded as illustrative and exemplary rather than restrictive orall-encompassing, and all such modifications to the specific embodimentsdescribed below are intended to be included within the scope of thepresent invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The detailed description that follows describes exemplary embodimentsand is not intended to be limited to the expressly disclosedcombination(s). Therefore, unless otherwise noted, features disclosedherein may be combined together to form additional combinations thatwere not otherwise shown for purposes of brevity.

The disclosure provided herein describes features in terms of preferredand exemplary embodiments thereof. Numerous other embodiments,modifications and variations within the scope and spirit of the appendedclaims will occur to persons of ordinary skill in the art from a reviewof this disclosure.

As used herein and in the appended claims, the term “comprises,”“comprising,” or variations thereof are intended to refer to anon-exclusive inclusion, such that a process, method, article ofmanufacture, or apparatus (e.g., a generator) that comprises a list ofelements does not include only those elements in the list, but mayinclude other elements not expressly listed or inherent to such process,method, article of manufacture, or apparatus.

The terms “a” or “an”, as used herein, are defined as one, or more thanone. The term “plurality”, as used herein, is defined as two, or morethan two. The term “another”, as used herein, is defined as at least asecond or more.

Unless otherwise indicated herein, the use of relational terms, if any,such as “first” and “second”, “top” and “bottom”, “back” and “front”,and “left” and “right” and the like are used solely to distinguish oneview, entity or action from another view, entity or action withoutnecessarily requiring or implying any actual such relationship, order orimportance between such views, entities or actions.

The terms “including” and/or “having”, as used herein, are defined ascomprising (i.e., open language).

As used herein “x-axis” or “first axis”, “y-axis” or “second axis” and“z-axis” or “third axis” mean three different geometric directions andplanes. Typically, the x-axis is used to indicate motion in a horizontaldirection/plane, the y-axis is used to indicate motion in the verticaldirection/plane and the z-axis is used to indicate motion in an axisthat is perpendicular to both the x and y axes. However, depending onthe orientation and supporting structure of an OPE and the origin of thethree axes may be interchangeable.

As used herein the phrase “operable to” means “functions to” unless thecontext or knowledge of one skilled in the art indicates otherwise.

To the extent any dimension, weight, size, percentages or operatingparameters are described herein or shown in the figures (collectively‘parameters”), it should be understood that such parameters arenon-limiting and merely exemplary to allow those skilled in the art tounderstand the inventive embodiments described herein.

Similar reference numbers may denote similar components and/or featuresthroughout the attached drawings.

Referring to FIG. 1 there is depicted a simplified block diagram of asystem 1 for producing power of at least 5 kWe that includes first andsecond generators 2, 3 and a control system. In embodiments, the system1 may be compact in size. For example, system 1 may replace threeexisting MIL SPEC generator systems. In an embodiment, the overallweight of system 1 may be at least 40% less than the weight of theexisting systems. For example, an existing system may weigh 740 lbs. ormore while an inventive, exemplary system 1 may weigh less than 400pounds (e.g., 375 to 400 lbs).

In an embodiment, the control system may comprise an electronic controlunit (“ECU”) 13 and control and data bus 14 (“control bus”), forexample, to name just two of the components making up an exemplarycontrol system.

The engine 2 a may be connected to the first and second generators 2, 3to provide energy to the first and second generators 2, 3. The engine 2a may be an OPE engine described in more detail herein. In anembodiment, the first generator 2 may be configured and operable tooutput at least 5 kWe of power during both “cold” and “hot” startconditions and provide such power at a wide array of voltages (e.g., 200to 600 Volts DC (VDC), such as 450 VDC) that can be used to power a widearray of electrical loads 7 (e.g., loads have load following capabilityfrom 2 kW to 5 kW) via distribution, electrical power bus 35(“distribution bus”).

In more detail, in an embodiment, upon generating an amount of power,the generator 2 may first output such power to a DC-to-DC powerconverter and conditioner 4 that is configured and operable to receivesuch power from the generator 2 at one or more input voltages (e.g., 200VDC to 600 VDC), convert the input voltage(s) to one or more loweroutput voltages (e.g., 450 VDC) and then output power at the one or morelower voltages to an electrical protection module 5, electrical powerinverter 6 and finally to one or more electrical loads 7 viadistribution bus 35 and electrical load connections 8. In embodiments,the inverter 6 may be configured and operable to receive direct current(DC) power from the converter 4 at one or more DC voltages (VDC),convert the DC voltages into or more alternating current voltages (VAC,e.g., 120 VAC, 240 VAC), for example, and output and supply such ACpower at the one or more AC voltages to one or more loads 7 viaconnections 8.

In an embodiment, the electrical protection module 5 may comprise one ormore electrical or electronic capacitors or capacitive components, forexample, configured to absorb energy from voltages and currents producedby the loads 7 that exceed the safe, operating capacity of the generator2 and converter 4 (e.g., voltage spikes, short-circuit loads) therebyprotecting the generator 2 and converter 4 from such unsafe voltages andcurrents.

FIG. 1 also depicts an exemplary DC battery 9 as a part of system 1. Inembodiments, the battery 9 may be operable to generate and output(sometimes collectively referred to as “supply”) power at one or more DCvoltages (e.g., 12 VDC 24 VDC) to the second generator 3 (e.g., DCpowered, electrical generator) and to one or more additional componentsof system 1, such as ECU 13, via system power bus 10 (“system bus”). Inembodiments, the second generator may be optionally operable to functionas an electrical or electronic starter or alternator, thus eliminatingthe need for a conventional starter motor, starter ring gear, andassociated wiring, for example.

In more detail, as required to start the engine of the generator 2, thebattery 9 may be operable to supply power at one or more DC voltages(e.g., 12 VDC 24 VDC) to the starter 3 (or second generator) via systembus 10. Upon receiving such power from the battery 9 the starter 3 maybe configured and operable to supply power to the ignition subsystem ofthe engine 2 a of the generator 2 at a suitable voltage and current toinitiate combustion and start the generator 2.

As shown the battery 9 may also supply power to (i) one or more fans 33,34 that are used as a part of a cooling module 35, (ii) one or morepumps 24 configured and operable to move coolant used to control thetemperature of the generator 2 (e.g., cool the engine of the generator),(iii) one or more component DC-to-DC converters 18 that are configuredand operable to convert one or more input DC voltages (e.g., 24 VDC)from the battery 9 to one or more output DC voltages (e.g., 12 VDC) andsupply power at the one or more output DC voltages to one or more systemindicators, such as lights, gauges 17 and/or user interface and display15 (collectively “user interface”), and (iv) to the control unit 13.

Additionally, the generator 2 and battery 9 may supply power tobatteries and components of an additional system 20 (e.g., a NATO 24 VDC“slave” system) via additional power bus 19 (e.g., a NATO style batteryconnection bus meeting MIL-PRF-62122 REF C) for example.

To provide a user with the capability to control both systems 1, 20 theinventors include a paralleling capability. In more detail, the controlunit 13 may be connected to a control unit (not shown) of the secondsystem 20 via a communication (not shown, e.g., a CAN-BUS communicationbus) to allow the two systems 1, 20 to exchange communication signalsto, among other things, control and/or synchronize the generator 2 ofsystem 1 with a generator of the second system 20 or with additionalbatteries (not shown).

The control unit 13 may be operable to send and receive electrical andelectronic control signals and/or data to and from one or morecomponents of the system 1 via control bus 14. For example, the controlunit 13 may receive signals representing instructions from the userinterface 15 (e.g., LCD display) in order to control the operation ofthe generator 2 using one or more redundant pathways as well ascontrolling other components of system 1, such as (a) the enginethrottle 22 which is configured and operable to regulate the amount ofair that is input into the engine 2 a of the generator 2, (b) one ormore ports 12 a that may input one or more types of diesel fuel 11 intothe engine 2 a via fuel supply line 12, (c) the DC-to DC converter 4 and(d) cooling fans 33, 34 to name just some of the components of system 1that may be controlled by the control unit 13. It should be understoodthat such control may be initiated by receipt of instructions from auser via user interface 15 and control bus 14, and/or, by electronicinstructions stored as signals and data within control unit 13 (e.g.,artificial intelligence control algorithms). That is to say, control ofcomponents of system 1 by control unit 13 may be initiated by receipt ofinstructions at control unit 13 from user interface 15 in real-time ormay be initiated by control 13 by accessing stored instructions in itsmemory, for example.

In addition to the control unit 13, the system 1 may include one or moremechanical switches (e.g., “ON” of “OFF” switches) that may beelectrically connected to one or more components of the system toredundantly control the operation of the system and/or as a mastercontrol override. The control unit 13 may include a wiring harness thatincludes a plurality of electrical wires configured in a 2-point wiringmethod thereby eliminating electrical/mechanical junctions or welds inthe harness for redundancy and durability (i.e., ruggedness).

To further increase the ruggedness of the system 1, the control unit 13may be encased in a conductive aluminum housing that is grounded to theengine's 2 a chassis to provide an added layer of protection againstunwanted electromagnetic interference (EMI). Still further,microelectronics and electronics (e.g., electronic processors) onprinted circuit boards within the control unit 13 may be encapsulated ina silicone material within the enclosure for enhanced vibrationisolation.

Referring now to FIGS. 14A to 14C, there are depicted views of exemplarycomponents of an exemplary, ruggedized enclosure 40. FIGS. 14 a and 14Bdepicts a ruggedized frame that includes horizontal and verticalperimeter beams 40 c, 40 d, 40 e and additional transverse support beams40 f that may be configured and positioned to support one or morehigh-strength, yet lightweight protective panels 40 g (e.g., carbonfiver panels) shown in FIG. 14C. In embodiments, the frame and panels 40g of the enclosure 40 may be configured to provide protection tocomponents of system 1 within the enclosure 40 from vibratory and otherunwanted forces or electrical signals. Optionally, the panels 40 g andbeams 40 c, 40 d, 40 e may be configured, and composed of a material toprovide protection against undesirable electromagnetic interference(EMI) (e.g., one or more EMI protective mesh layers) and/or the system 1may include one or more EMI snubber circuits.

FIG. 14A also depicts exemplary positions p₁, p₂ within the ruggedizedenclosure where the power electronics 43 (e.g., DC-to-DC power converterand conditioner 4, DC to AC inverter 6) may be positioned depending onthe volume required by such components 43 and the available space(volume) within enclosure 40 while FIG. 14B depicts exemplary positionswithin frame that may receive one or more sound attenuating and/orabsorbing layers. In an embodiment the one or more layers of the soundattenuating and/or absorbing layers may be composed on a melamine foam,for example, that may have an exemplary thickness of 2 inches, forexample. Still further, such a configuration may provide sound and noiseattenuation to a level of 1.0 NRC (noise reduction coefficient) at 500Hertz as part of an overall sound attenuation subsystem.

FIGS. 14D to 14F depict views of additional features of a soundattenuation subsystem. In more detail, there is shown an exemplaryengine mounting structure 40 h positioned within the enclosure 40.Though only a single structure 40 h is shown, it should be understoodthat the system may include a plurality of such structures 40 h.

Each such structure 40 h may be operable to support components of thesystem 1, including the engine 2 and generators 2, 3. In an embodiment,the structure 40 h may comprise a washer 40 j (e.g., snubbing washer)connected to a plate 40 i (see FIGS. 14E and 14F). The combination ofwasher and plate may be fastened to the enclosure using fasteners (e.g.,screws, welds, etc.) received within openings 40 n (see FIG. 14F) of theplate 40 i. To connect and support the system 1, one end of one or moresupport stubs 401 may be received into each opening 40 m of the washer40 n while a second end of the stub 40 i may be received into an openingin base 40 k of the frame that supports the system 1. In embodiments, itis believed that such structures provide an axial stiffness of 450lbs./inch and a radial stiffness of 75 lb./inch. Accordingly, it isbelieved that such structures 40 h provide a degree of ruggedizedstability to the system 1 which, in turn, reduces the chances thatcomponents of system 1 may move or vibrate during operation, thus aidingin the reduction of unwanted noise and sounds from system 1.

Referring back to FIG. 1 , the system 1 may also include a intake aircharge heater 21 (e.g., grid heater) that is configured and operable topre-heat an amount of atmospheric air that flows through and/or over theheater 21 where the amount may be determined and provided by thethrottle 22 based on control signals from the control unit 13, forexample, particularly, during the initial start-up of the engine 2 a.Heater 21 may be operable to output the pre-heated air via a manifold 23to valves that are positioned on a cylinder of the engine 2 a of thegenerator 2 (valves not shown in FIG. 1 ) so that the air may be fed toa combustion chamber of the engine 2 a. In an embodiment, the heater 21may pre-heat the air to a minimum of 100° F. above ambient, for example.

To control the temperature of components of the system 1, the system 1may include a thermal management subsystem. In an embodiment, thesubsystem may include one or more pumps 24, piping 25, 26, fans 33, 34and cooling module 35. Further, as shown in FIG. 2 , the subsystem mayalso comprise a thermal transfer structure 36 (e.g., a heat sink),additional piping 37, one or more thermostat mechanisms 38, a de-gassingtank 39, fans 33, 34 and air flow 41 a. In one embodiment, the coolingmodule 35 may include a plurality of chambers or structures, such as aradiator 28 and a separate muffler 29 and exhaust mixing chamber 30.

In an embodiment the degassing tank 39 may comprise a reservoir forholding the liquid coolant and a vent to allow gases entrapped in thecoolant to be vented or expelled from the coolant. The degassing tank 39may typically be configured and operable to maintain a pressure of about15 PSI so that the coolant circulates through the degassing tank 39 andcooling loops.

The thermal management subsystem may operate using one or more differentcirculation loops. For example a first loop 25 a may be a “warm-up’loop, a second loop may be a “cooling loop” 26 a, a third loop may be anoil cooling loop 38 a and a fourth loop may be a component thermaltransfer loop 37 a, for example.

In an embodiment, the first loop 25 a may operate as follows. Uponstart-up of the engine 2 a of the generator 2 the one or more thermostatmechanisms 38 may be operable to detect the temperature of a liquid,engine coolant and remain in an initial state (e.g., a “closed”position). In more detail, the one or more thermostat mechanisms maycomprise a temperature sensor for detecting the temperature of thecoolant and one or more multi-positional valves. When the engine 2 a isstarting the temperature of the coolant is typically low and thus, thetemperature detected by the sensor is typically below a first thresholdthat would trigger a change in the state of the valve. Accordingly thevalve may remain in an initial state (e.g., again, a closed position).Accordingly, coolant within piping 25 may circulate within loop 25 aunder pressure from pumps 24.

In an embodiment, the second loop 26 a (“cooling loop”) may operate asfollows. After the engine 2 a has started up and has been operating thetemperature of the coolant may be begin to rise, and thus, thetemperature detected by the sensor of the thermostat mechanism 38 maytypically reach and exceed the first threshold that triggers a change inthe state of the valve of the thermostat mechanism 38. Accordingly thevalve may move from an initial state to an adjusted state (e.g., an openposition) that allows coolant to flow through piping 25 and piping 26.Accordingly, heated coolant within piping 25, 26 may circulate withinloop 26 a. In more detail, heated coolant from the engine may passthrough radiator 28. In an embodiment, fan (or fans) 33 may be operableto force air 41 a that is flowing over the radiator 28 containing theheated coolant to cool the coolant by reducing its temperature. Tocontrol the operation of the fans 33, the thermal management system mayinclude another temperature sensor 31 (see FIG. 1 ). In one embodiment,when the sensor 31 (e.g., thermostat, thermocouple) detects that thetemperature of the coolant has met and/or exceeded a second threshold(which may or may not be the same as the first threshold) the sensor 31sends a signal to the fans 33 to turn on and force air 41 a through theradiator to cool the coolant. The now cooled coolant continues to flowthrough piping 26, 25 and pumps 24 where it is forced back to the engine2 a.

In an embodiment, the third loop 38 a (“oil cooling loop”) may operateas follows. During start-up, and/or after the engine 2 a has started upand has been operating it may be necessary to cool or warm the oil thatis being used to lubricate the engine 2 a. In an embodiment the oil maybe stored in an oil chamber 42. Accordingly, after the engine 2 a hasstarted up and has been operating the temperature of the coolant may bebegin to rise, and thus, the temperature detected by the temperaturesensor of the thermostat mechanism 38 may typically reach and exceed thefirst threshold that triggers a change in the state of the valve of thethermostat mechanism 38. Accordingly the valve may move from an initialstate to an adjusted state (e.g., an open position) that allows coolantto flow through piping 38 b, 25 and 26. Thus, heated coolant withinpiping 25, 26 and 38 may circulate within loop 38 a.

In an embodiment, the fourth loop 37 a (“component thermal transferloop”) may operate as follows. Similar to the second loop, after theengine 2 a has started up and has been operating the temperature of thecoolant may be begin to rise, and thus, the temperature detected by thetemperature sensor of the thermostat mechanism 38 may typically reachand exceed the first threshold that triggers a change in the state ofthe valve of the thermostat mechanism 38. Accordingly the valve may movefrom an initial state to an adjusted state (e.g., an open position) thatallows coolant to flow through piping 25 and piping 26 towards radiator28. In more detail, heated coolant from the engine may pass throughradiator 28 and be cooled as described previously. In addition, ratherthan just return to the engine 2 a some of the now cooled coolant maypass through piping 37 and be directed towards the thermal transferstructure 36 (e.g., a heat sink), the configuration of which is setforth in more detail elsewhere herein. The cooled coolant absorbs heatfrom the structure 36 that originates with the operation of electroniccomponents 43 (e.g., DC-to-DC converter 4, DC-to-AC inverter 6, and/orliquid cooled alternators) and carries the absorbed heat in the coolantthat flows through piping 37, 25 and 26 and eventually back to theradiator 28 to be cooled once again.

FIGS. 15 a to 15C depict views of the thermal transfer structure 36.FIG. 15A depicts a view of the top of the structure 36 (facing away fromelectronic components 43). FIG. 15B depicts a view of the structure(facing towards the components 43) and FIG. 15C depicts a view of thestructure 36 positioned on the components 43.

As shown in FIG. 15A, structure 36 may comprise a plate-like or bar-likestructure. One side of the structure 36 may include a plurality ofcooling fins 36 a. In embodiments, as the temperature of the electroniccomponents increases, some of the thermal energy from the components 43may be conducted or conveyed to the structure 36, and eventually to thefins 36 a. As air 41 a in the cavity 46 of the system 1 flows, the airflows around and over each fin 36 a, thereby removing thermal energyform each fin 36 a and aiding in the cooling of the components 43.

In an embodiment, the structure 36 may also be cooled by coolant frompiping 37 as shown in FIG. 2 . In an embodiment the structure 36 maycomprise openings 36 b to receive piping 37 and any necessary fittings,for example. As the coolant flows into the structure 36 from the coolingmodule 35 it also flows into internal cavities of each fin 36 a, therebytransferring thermal energy (heat) from each fin 36 a and from the otherportions and surfaces of the structure 36 as well to the coolant. Suchthermal transfer functions to cool the structure 36 and aids in thecooling of the components 43.

In an embodiment, the structure 36 may be composed of 6061 T6 aluminum,to give just one example of a material that may be used as structure 36.

The inventors believe that the addition of the structure 36 and coolingloop 37 a substantially reduces the temperature of the power electronics43.

In addition to the liquid coolant, cooling loops the thermal managementsubsystem is also configured to provide air flow cooling. For example,in one embodiment the system 1 may include a ruggedized frame 40 thatsurrounds and protects the generator 2, engine 2 a and other componentsof system 1. In one embodiment the frame 40 may include an inlet 40 a toallow air outside of the frame 40 at an input temperature T_(ambient) toenter into an internal cavity 46 formed by the frame 40 and an outlet 40b that allows heated air at temperature T_(inside) to exit the cavity 46in order to cool internal components of the system 1, where, in general,T_(ambient) is less than T_(inside) during operation of the generator 2and engine 2 a.

Once inside frame 40, the air at T_(ambient) the air in the cavity mayflow over (or through) generators 2,3, engine 2 a, electronics 43,radiator 28, muffler 29 and is used by fans 33, 34 to cool the liquidengine coolant in loops 25 a, 26 a 37 a and 38 a as well as cool thegaseous exhaust from the engine.

In more detail, referring to FIG. 3 there is shown an exemplaryconfiguration of the radiator 28, muffler 29 and exhaust mixer 30 thatmay be enclosed by a heat transfer and rejection chamber 30 b. Aspreviously explained, air at an ambient temperature T_(ambient) may flowthrough the radiator 28 in order to cool the liquid coolant inside theradiator. Typically, the temperature T_(radiator) of the subsequentlyheated air is above the temperature of the input air T_(ambient).However, the temperature T_(radiator) of the so-heated air may betypically less than the temperature T_(muffler) of the exhaust gasesthat are typically output from the muffler 29. The inventors discoveredthat by mixing at least the air that has flowed over the radiator withthe exhaust gases that exit the muffler 29 in the exhaust mixer 30 itwas possible to reduce the temperature T_(output) of the air-gas mixturethat is ultimately output from the cavity 46 via outlet 40 b in theframe 40.

In more detail, in an embodiment exhaust gases from the operation of theengine 2 a may be expelled from the combustion chamber(s) of the engine2 a via exhaust port 44 and fed to muffler 29 via exhaust piping 44 awhich may comprise a portion of flexible piping 44 b that is configuredfor vibration isolation (e.g. bellows, wire rope mounts). The exhaustgases output from the muffler 29 at the temperature T_(muffler) may beinput into a chamber of the exhaust mixer 30. In addition, the exhaustmixer 30 may be further configured to receive a second input of air thathas flowed through the radiator 28 and has a temperature T_(radiator)into its chamber. In an embodiment, the chamber of the exhaust mixer 30may be configured and operable to mix the air that has flowed throughthe radiator 28 with the exhaust gases that have exited the muffler 29.The mixing of the two inputs, where the temperature T_(radiator) of thesecond input from the radiator 28 is substantially less than thetemperature T_(muffler) of the gases output from the muffler 29 reducesthe temperature T_(output) of the air-gas mixture that is output fromthe cavity 46 via outlet 40 b in the frame 40. In sum, the inventorsdiscovered that the air that has flowed through the radiator 28 can beused to reduce the reduce the temperature of the exhaust gases exitingthe muffler 29 in order to reduce the temperature of the air-gas mixturethat is output from the cavity 46 via outlet 40 b in the frame 40.

The inventors further discovered an additional configuration of theradiator 28, muffler 29 and exhaust mixer 30 that provides air flowcooling. In this embodiment, the muffler 29 may comprise one or moreexternal surface, cooling fins and external baffles 30 a that areconfigured to transfer energy (e.g., thermal energy) from the externalsurface of the muffler 29 to the air that is flowing over the baffles 30a to heat the air to a temperature T_(muffler-skin). Further, the nowheated air (and other air that has flowed over additional components ofthe system 1, such as components 43) within chamber 30 b may be directedby air forced into chamber 30 b by exhaust fan 34 may be operable toforce air that has flowed over the muffler and other components of thesystem 1 (e.g., components 43) into the chamber of the exhaust mixer 30where it may be mixed with air at that has flowed through the radiatorat a temperature T_(radiator). Thereafter, the now combined and mixedair at temperatures T_(muffler-skin) and T_(muffler-skin) may be inputinto the exhaust mixer 30 at a temperature T_(combined). In anembodiment, the chamber of the exhaust mixer 30 may be furtherconfigured and operable to mix such a combination of heated air at atemperature T_(combined) with the exhaust gases that have exited themuffler 29. The mixing of the inputs, where the temperature T_(combined)is substantially less than the temperature T_(muffler) of the gasesoutput from the muffler 29 reduces the temperature T_(output) of theair-gas mixture that is output from the cavity 46 via outlet 40 b in theframe 40. In sum, the inventors discovered that the air that has flowedthrough the radiator 28 and over and through the muffler 29 (as well asother components within frame 40) may be used to reduce the temperatureof the exhaust gases exiting the muffler 29 in order to reduce thetemperature of the air-gas mixture that is output from the cavity 46 viaoutlet 40 b in the frame 40.

Though not shown in FIG. 3 , to insure that air does not escape from thechamber 30 b via the opening in the chamber 30 b, that allows the fan 34to force air into the chamber 30 b, the system 1 may include a one-wayvalve and/or pressure sensor. In an embodiment, the sensor may sensethat pressure drop across the opening for the fan exceeds a thresholdamount (e.g., a positive pressure) upon which the valve may close theopening to restrict air from within the chamber 30 b from escaping. Thismay occur, for example, when the fan is in an “OFF: state ormalfunctions, for example.

In addition to being a part of a thermal energy management subsystem,the muffler 29 and exhaust mixer 30 may also form a sound attenuationsubsystem.

In an embodiment, the muffler 29 may further comprise an internal,shaped baffle chamber (e.g., rectangular) that includes a multi-passperforated aluminum or shell structure that may be configured andoperable to attenuate the decibel level of the exhaust gases. Thereduced-decibel, exhaust gases that exit the muffler 29 may be inputinto the exhaust mixer 30 where they may be mixed with heated air asdescribed above.

The external baffles 30 a and exhaust mixer 30 may be configured tofurther attenuate the decibel level of the air-gas mixture that isoutput from the cavity 46 and muffler 29. In an embodiment, the exhaustmixer 30 may comprise a chamber for audibly mixing the exhaust gases andheated air from the cavity 46 (e.g., air that flows through the radiator28, and through and over the muffler 29 and/or other components). Suchmixing is believed to substantially reduce the decibel level of theair-gas mixture that is output from the cavity 46 via outlet 40 b.

FIG. 4 depicts experimental results of the sound attenuation provided bythe muffler 29 and exhaust mixer 30. In an embodiment the decibel levelof the air-gas mixture output from the cavity 46 after passing throughthe muffler 29 and exhaust mixer 30 was less than 70 dBa for an engine,such as engine 2 a, that was operating at 3800 RPM measured by amicrophone positioned within 10 meters of the exhaust outlet 40 b, forexample.

Referring now to FIGS. 5A and 5B there are depicted front and back viewsof an exemplary engine 2 a and generators 2, 3 (the starter 3 may alsobe referred to as a low-voltage generator) that may be used with thesystem 1. In one embodiment the engine 2 a may comprise an inwardlyopposed piston engine or OPE operable using both gaseous fuel and/orliquid fuel types. The reader is also referred to the “253 Application”reference above for additional features of the engine 2 a, all of whichare incorporated by reference herein in full. To the extent that thepresent discussion of the engine 2 a conflicts with the disclosure ofthe OPE in the '253 Application, the reader is advised that the presentdisclosure governs. However, where possible to those skilled in the art,the disclosure of the '253 Application and the present disclosure are tobe interpreted as describing various different, but complimentary,features of inwardly opposed piston engines.

Though the discussion herein may use an OPE as an exemplary engine toprovide energy to generators 2, 3, loads 7, paralleled system 20 and/orone or more batteries it should be understood that this is just one typeof engine that may be used to power such components as well as othercomponents of system 1.

The front view in FIG. 5A depicts the OPE engine 2 a (“engine”hereafter), high-voltage generator 2, low-voltage generator 3, port fuelinjector subsystem 12 b, direct injection subsystem 12 a, oil filter 2g, oil sump pump 2 f, fuel pump 11 a (for one or more types of fuel),air intake assembly 2 e that enables a flow of combustible air into theinterior of a cylinder of the engine 2 a during an intake portion of acombustion cycle and engine exhaust assembly 44 that is operable toenable a flow of exhaust and combustion by-products out of the interiorof the cylinder during an exhaust portion of the combustion cycle whilethe back view in FIG. 5B depicts some of the same components, and, inaddition, one or more spark plugs 2 j, crank wheels 2 k, 2 l, intake andexhaust cams 2 h, 2 i, intake air charge heater 21 (e.g., grid heater)and assorted pulleys and corresponding, connecting chains (e.g., metalchain) or belts (e.g., neoprene rubber) or gears, though it should benoted that a combination of different drive systems may also be used,including an electrical actuator depending on the requirements of aspecific application.

As seen in FIGS. 5A and 5B the high-voltage generator 2 and low-voltagegenerator 3 may be connected to different, opposing cranks (andcorresponding crankshaft). For example the high-voltage generator 2 maybe directly connected to crank 2 l while the low voltage generator 3(used as a starter) may be directly connected to crank 2 k, for example,without the need to use additional pulleys, brackets and/or belts. Thisconfiguration substantially reduces parasitic drag forces that may arisewhen such components (pulleys, brackets and/or belts) are used, thusincreasing the efficiency of the system 1.

While FIGS. 5A and 5B may show one configuration of intake and exhaustassemblies, a desired number of intake and exhaust assemblies may beprovided, having a desired shape and/or axial orientation with respectto each other and any desired spatial arrangement to meet therequirements of a particular engine configuration, depending on suchfactors as the geometry of the end-use envelope in which the engine isto be installed, and/or the air and exhaust volumetric flow raterequirements for the desired combustion reaction or cycle. Stillfurther, the characteristics/shape/form of structures (e.g., thecylinder) surrounding the assemblies may be specified so as to enablethe use of valves of a certain type or to enable the mounting of thevalves at desired locations along the cylinder of the engine 2 a tocontrol intake and exhaust flow, and other pertinent factors. That is tosay, the number, size, shape and locations of valve apertures in theassemblies may be varied and specified to meet the requirements of aparticular engine design (i.e., geometry and/or operation of the OPEengine 2 a, for example). That said, in an embodiment, both the intakeand exhaust assemblies 2 e, 44 (e.g., the valves included in suchassemblies) may be configured to operate at top dead center (TDC) of thecombustion cycle. Accordingly, exemplary engine 2 a is capable ofinducting air, igniting and burning fuel and expelling exhaust gases infour separate strokes and need not rely on positive pressure across theintake assembly to exhaust gases.

The intake and exhaust assemblies 2 e, 44 may include removable intakeand exhaust valve assemblies, respectively. Thus an inventive engine 2 aneed not include a typical cylinder head as in a traditional engine.This provides a number of advantages. For example, a cylinder head mayfunction as a heat sink due to the fact that it typically comprises alarge surface area and it is proximate to combustion events, therebyexposing the head to the entirety of the heart discharged by thecombustion events. This typically leads to a loss of energy due to theconversion of energy form work into heat. However, because the inventiveengine 2 a does not use a typical cylinder head (i.e., when the engine 2a is an OPE), such losses are minimized (i.e., the inventive engine 2 aconverts more fuel into work and less into heat than typical,traditional engines). Further, the modular, removable valve assemblies(e.g., intake and exhaust assemblies) allow for ease of servicing,lowered production costs. In embodiments the modular intake and exhaustassemblies 2 e, 44 may be directly affixed (connected) to a cylinder ofthe engine 2 a, thus increasing the overall simplicity and practicalityof the inventive engine 2 a. That is to say, in general, because theinventive engine 2 a does not need to incorporate a cylinder head theintake and exhaust assemblies can be directly connected to the engineblock, rather than be connected to the head. As a result, the inventiveengine 2 a may be more compact and weigh less than traditional engines.It should be noted that intake and exhaust valve assemblies made a partof an inventive engine 2 a need not necessarily be configured to beactuated in an overhead configuration. Alternatively, such valveassemblies may be actuated by a push-rod and camshaft combination, forexample.

Continuing, the inventive engine 2 a may comprise a four-cycle orfour-stroke engine and while the figures herein may show only onecylinder of the engine 2 a for clarity, it should be understood that oneor more cylinders may be utilized depending on the amount of powerdesired to be produced by the engine 2 a (e.g., two or more cylinders).That said, it should be understood that the structural arrangements andoperating principles described herein may alternatively be applied to aninventive, two-stroke OPE. In an embodiment, each cylinder comprises oneor more inwardly opposed pistons (see FIG. 2 of the '253 Application,elements 7a, 7b).

In embodiments of the invention, the inventive engine described hereinmay be configured to provide energy to a generator, such as generator 2,to output at least 5 kWe of power.

The opposed, inwardly facing pistons of the engine 2 a may havepredetermined lengths and predetermined diameters. In one embodiment,the stroke length of each of the opposed pistons of the engine 2 a maybe twice the amount of a conventional engine, for example, it beingunderstood that the piston lengths may be geometrically determined inaccordance with the piston stroke length and the lengths of aperturesformed in a wall of the cylinders through which flow exhaust gases andair for combustion (e.g., see element 5a in FIG. 3C of the '253Application).

Thus, the total difference between the spacing of the pistons at closestapproach to each other (i.e., at “top dead center”) and the maximumspacing of the pistons during the engine cycle (i.e., at “bottom deadcenter”) may also be twice the amount of a conventional engine, forexample.

As noted previously, the exemplary engine 2 a may be a four-stroke, OPEtype of engine. In an embodiment, both the intake and exhaust assemblies2 e, 44 (e.g., the vertically opposed (from a center line of a cylinder)valves included in such assemblies) may be configured to operate at topdead center (TDC) of the combustion cycle, though, as previously statedan OPE is just one type of engine that may be used to power componentsof system 1.

An OPE type of engine 2 a can induct air, ignite and burn fuel and expelexhaust gases in four separate strokes and need not rely on positivepressure across the intake assembly to exhaust gases.

Exemplary engines 2 a described herein may operate using one or morecombustion modes, such as spark ignition (SI), compression (CI), SA-CI,partially-premixed combustion compression ignition (PPCI) or gasolinedirect-injection compression-ignition (GCI), for example.

Referring to FIGS. 16A to 16D there are shown views of exemplary intakeand exhaust valve assembly configurations of an exemplary OPE engineaccording to embodiments of the invention. Again, an OPE is only onetype of engine that may be used with system 1. In more detail, theconfigurations in FIGS. 16A and 16B address the opening of the intakevalve 2 ee and closing of the exhaust valve 44 e in such a way thattheir movement/position does not interfere with the movement of apiston(s).

In more detail, in an embodiment the mounting area thickness between thehousing of the valve assemblies (e.g., 2 ee, 44 e) may be increased byan amount (e.g., 0.480 inch) according to a desired position (lobe) of acam 2 hh so that when a valve of an assembly fully opens the valve doesnot penetrate the inside circumference of the combustion area of thecylinder 2 n.

For example, in FIG. 16A the intake and exhaust valve assemblies 2 ee,44 e may be configured such that the valves 2 ee, 44 e are positionedon, or near, a valve seat boundary, VSB, instead of an interferenceboundary, IB, of the cylinder 2 n such that when the piston (not shown)moves through the cylinder during a combustion cycle, the piston andvalves 2 ee, 44 e do not interfere with one another. In this embodimentthe valves may be actuated or moved using a single over-cylinder camshaft 2 hh and rocker arm 2 ii.

In FIG. 16B, the intake and exhaust valve assemblies 2 ee, 44 e may beconfigured such that they positioned on, or near, a valve seat boundary,VSB, instead of an interference boundary, IB, of the cylinder 2 n suchthat when the piston (not shown) moves through the cylinder during acombustion cycle, the piston and valves 2 ee, 44 e do not interfere withone another. In this embodiment the valves 2 ee, 44 e may beindividually actuated by respective cams and cam shafts 2 h, 2 hj(shafts are not shown for clarity).

In an embodiment, the exemplary intake valve 2 ee may operate asfollows. During actuation, and as the cam 2 hh moves to one position(i.e., lobe), the valve 2 ee may be actuated but held in a fixedposition outside the interference boundary IB until a piston clears theIB. Thereafter, the valve 2 ee may be fully opened as the cam 2 hh movesto a second position.

As for the exhaust valve 44 e, as the cam 2 hh moves to a first position(i.e., lobe) the valve 44 e may be retracted slightly so as not tointerfere with the movement of a piston(s). Thereafter the valve 44 emay be fully closed as the piston(s) reaches TDC.

The positioning of valves 2 ee, 44 e on the same side of the cylinder 2n as shown in FIGS. 16 a and 16B allows for the positioning of the sparkplug 2 j, 2 jj at a wide number of angles (e.g., 0 to 270 degrees).

Still further, when an exemplary engine 2 a comprises multiple cylinders(e.g., 3 or more) and the cylinders are placed close to one another(e.g., side-by-side) the ability to position the spark plug 2 j, 2 jj ata wide range of angles may be advantageous.

Referring now to FIGS. 16C and 16D there are shown alternativeconfigurations of valve assembles 2 ee, 44 e to avoid interference withthe movement of a piston(s). FIG. 16C depicts a side view of theconfiguration while FIG. 16D depicts a top view of the sameconfiguration. In both figures, the valve assembles may be seated orotherwise configured such that the valves of each assembly (e.g., intakeand exhaust valves) are outside the outside diameter of the cylinder 2 nas the piston 2 z moves inside the cylinder.

The inventors discovered a number of different engine cylindercombustion configurations that provide an appropriate fuel-air mixturethat may be incorporated into the exemplary engine 2 a. In embodiments,the engine 2 a may include a dual Injector, fuel subsystem. Moreparticularly, in the embodiments described herein the engine may includea port fueled injector (PFI) and a direct injector (DI) (e.g., an M6injector) that may have one or more output nozzles. In an embodiment,the DI is configured to provide high-pressure fuel delivery. Suchpressures are required to atomize one or more fuels that may be usedwith the system 1 (e.g., JP-8 fuel). Moreover, the fuel can be injectedin a single-stage or multi-stage. Staged injection provides for theopportunity to rate shape the combustion pressures, which can lowerknocking characteristics and pre-detonation. Additionally, the DI allowsmore control over the combustion process.

Further, in the embodiments described herein the engine 2 a may includea glow plug (e.g., an M10 glow plug) and at least one spark plug (e.g.,an M12 long reach spark plug) that may be positioned and mounted on acylinder (e.g., an M5 cylinder) of the engine 2 a. In those embodimentsthat include a long-reach spark plug (see, for example, FIGS. 6A, 6B, 8,9 and 10 ) the inventors believe that the inclusion of such a spark plugwith its addition length versus traditional spark plugs allows forignition and combustion close to the center of the combustion chamber Cand results in symmetrical flame propagation throughout the combustionchamber of an engine's cylinder and minimizes undesirable engine“knocking”. Accordingly, in such configurations the exemplary engine 2 amay comprise one or more cylinders, where each cylinder comprises atleast one long-reach spark plug for ignition and combustion close to acenter of a combustion chamber C of each cylinder.

One or more of the glow plug, spark plug and DI injector may bepositioned on the central perpendicular axis (“central axis”) of anengine's cylinder and/or may be positioned at an angle from the centralaxis of the cylinder based on the (i) cone angle and fuel spray patternof the direct injector, (ii) air flow, (iii) turbulence in thecombustion chamber, and (iv) the presence of staged injection.

In more detail, at temperatures below an ambient operating temperature,the temperatures and pressures required for combustion may be lacking.Accordingly, in an embodiment the engine 2 a may include a glow plug ineach of the engine cylinder configurations. More particularly, the glowplug may be configured as a compact structure and may be operable tooutput heat. Further, exemplary glow plugs described herein may beoperate using a 12 volt (V) power supply (not shown in figures) and maybe controlled by the electronic control unit 13.

Continuing, an exemplary glow plug and at least one exemplary spark plugmay be mounted based on the fuel spray pattern of the direct injector toprovide ignition, especially under cold start conditions (i.e.,temperatures that are below an engine's optimum operating temperature,e.g., below an ambient temperature, or an engine that has been inactiveor abandoned for a significant amount of time such as weeks, months,years or even decades). The glow plug and spark plug may be positionedto create rich pockets of fuel around the spark plug and glow plug toinitiate combustion under such conditions.

In some engine cylinder configurations discussed herein, a spark plugmay be positioned at a position that is above the center axis of acylinder while a glow plug may be configured at a position below thecenter axis. The inventors believe that mounting the spark plug awayfrom the center axis of the cylinder may improve the ability of theengine to be cooled due to a reduction in flame propagation and anexpected combustion rate when compared to a spark plug that may beconfigured along the center axis. Conversely, when faster combustiontimes are required or desired it may be advantageous to position thespark plug along the center axis of a cylinder.

Referring now to FIGS. 6A and 6B, there is depicted one suchconfiguration of the engine 2 a. In an embodiment, the engine 2 a maycomprise a dual Injector, fuel subsystem. In this embodiment, the firstfuel injector may be a PFI 12 b while the second fuel injector 12 a maybe a DI (e.g., M6 injector). Also shown in FIG. 6B is a spark plug 2 jand glow plug 2 m for igniting the fuel (e.g., JP-8 fuel) injected byinjectors 12 a, 12 b mixed air in the main chamber C, where in thisembodiment the DI 12 a and glow plug 2 m may be configured (i.e.,positioned and mounted) on one side of the cylinder 2 n (e.g., an M5cylinder) and the spark plug 2 j may be configured on the opposite sideof the cylinder 2 n. In an embodiment, the spark plug 2 j may beconfigured along the center axis of the cylinder 2 n to provide fastercombustion as compared to configuring the spark plug at an angle fromsuch a central axis. In an embodiment, the spark plug 2 j may comprisean M12 long reach spark plug, for example while the glow plug 2 m maycomprise an M10 glow plug to name two exemplary examples of suchcomponents. In an embodiment, the glow plug 2 m may be energized when itis necessary to ignite the fuel under “cold start” conditions inconjunction with the operation of the heater 21. During cold startconditions the fuel spray from the DI 12 a (from one or more of the DI's12 a nozzles) onto the spark plug 2 j and glow plug 2 m is believed tocreate concentrated pockets of fuel around the plugs. These concentratedor rich pockets of fuel are believed to promote the combustion processduring cold start conditions. Conversely, during hot start conditions,the glow plug 2 m may be de-energized (i.e., turned off) and combustionwill be initiated by the spark plug 2 j. The inventors discovered thatsuch a configuration provided a sufficient fuel mixture needed to startthe engine 2 a under cold-start conditions while providing sufficientpower when the engine 2 a is connected to one or more loads 7 withreduced engines knocking.

In this embodiment, fuel from the PFI 12 a and DI 12 a may be injectedinto the combustion chamber C. As the fuel begins to vaporizes, the fuel(and compressed air) may be ignited by the tip of the glow plug 2 mand/or spark plug 2 j as required at respective ignition zones I₁, I₂for example.

FIGS. 7A to 7C depicts views of an exemplary fuel delivery subsystem. Asshown in FIG. 7A, fuel 11 at one pressure (e.g., a low pressure) may beinput into a fuel pump 11 a at inlet 11 b. The pump 11 a may be operableto increase the pressure of the fuel to and deliver the fuel at anincreased pressure (e.g., a high pressure) to the DI 12 a and PFI 12 bvia high pressure fuel lines 12 c.

Referring now to FIGS. 7B and 7C, each of the fuel injectors 12 a, 12 bmay be securely connected to the engine 2 a by exemplary injector tiedowns and fuel rail structures. FIG. 7B depicts a view of the tie downsand rail 12 d for the PFI 12 b while FIG. 7C depicts a view of theexemplary tie downs and rail 12 e for the PFI 12 a.

It should be understood, however, that the engine cylinder configurationshown in FIGS. 6A, 6B and 7A to 7C excludes the positioning ofvertically opposed (from a center line of a cylinder) intake and exhaustvalves for the sake of clarity. Further, it should be understood thatthe engine cylinder configuration shown in FIGS. 6A, 6B and 7A to 7C isonly one exemplary engine cylinder configuration of the spark plug, glowplug and injectors. FIGS. 8 through 12 depict additional exemplaryengine cylinder configurations for exemplary spark plug, glow plug andinjectors, among other engine components where, again, theseconfigurations exclude the positioning of intake and exhaust valves forthe sake of clarity. Unless otherwise stated, the engine cylinderconfigurations set forth in FIGS. 8 to 12 may comprise the same type ofcylinders, injectors, glow plugs and spark plugs as indicatedpreviously.

In the exemplary configuration shown in FIG. 8 , both the spark plug 2 jand glow plug 2 m may be positioned on the same side of the cylinder 2n—on a side opposite the DI 12 a. As before, fuel from the DI 12 a (fromone or more of the DI's 12 a nozzles) may be direct injected into thecombustion chamber C. As the fuel is injected it begins to vaporize. Inthis embodiment, the DI 12 a may be configured at an angle such that thefuel spray 12 aa from one or more of the DI's 12 a nozzles may beslightly directed towards the glow plug 2 m. In an embodiment, the soconfigured DI 12 a allows some fuel (e.g., liquid fuel) within fuelspray 12 aa to land on a tip of the glow plug 2 m to provide ignition atzone I₁, for example, of the fuel by the glow plug 2 m during cold startconditions, for example.

The fuel from the DI 12 a may also travel towards the circumference ofcylinder liner (see exemplary path 12 ab) so that the fuel may bere-directed across the spark plug 2 j for additional ignition at zoneI₂, for example. In an embodiment, a flame from the spark plug ignitionmay propagate symmetrically across the combustion chamber C.

In the exemplary configuration shown in FIG. 9 , the spark plug 2 j andglow plug 2 m may be positioned on opposite sides of the cylinder 2 n.Further both the spark plug 2 j and DI 12 a may be positioned on thecentral axis of the cylinder on opposing sides of the cylinder. In thisconfiguration the engine 2 a may also include a pressure sensor 2 p(e.g., transducer) for monitoring the pressure within the combustionchamber C of the cylinder 2 n.

As before, fuel from one or more of the DI's 12 a nozzles may be directinjected into the combustion chamber C. As the fuel is injected itbegins to vaporize. In this embodiment, because the DI 12 a may beconfigured along the central axis of the cylinder 2 n, the fuel spray 12aa from one or more of the DI's 12 a nozzles may be directed towards theglow plug 2 m, allowing fuel (e.g., liquid fuel) within fuel spray 12 aato land on a tip of the glow plug 2 m to provide ignition of the fuel atzone I₁ along with mixed air in the main chamber C, for example, by theglow plug 2 m during cold start conditions, for example. The fuel fromthe DI 12 a may also travel towards the circumference of cylinder liner(see exemplary path 12 ab) so that the fuel may be directed andre-directed across the spark plug 2 j for additional ignition at zone I₂along with mixed air in the main chamber C, for example. In anembodiment, a flame from the spark plug ignition may propagatesymmetrically across the combustion chamber C.

In the exemplary configuration shown in FIG. 10 , the spark plug 2 j andglow plug 2 m may be positioned on the same sides of the cylinder 2 n.Further, this configuration includes two DI injectors 12 a, 12 a″ eachpositioned on opposite sides of the cylinder 2 n along the central axisof the cylinder 2 n. In this embodiment, as fuel is injected into thecombustion chamber C by the injectors 12 a, 12 a″ the fuel begins tovaporize and may be ignited by the tip of the glow plug 2 m atrespective ignition zone I₁ and by spark plug 2 j at respective ignitionzone I₂, for example. In more detail, the first injector 12 a may beconfigured such that fuel spray 12 aa from one or more of its nozzles isdirected at an angle towards the glow plug 2 m while the second injector12 a may be configured such that fuel spray 12 aa″ from one or more ofits nozzles is directed at an angle towards the spark plug 2 j. Inaddition, fuel spray from both injectors 12 a, 12 a″ may also traveltowards the circumference of cylinder liner so that the fuel may bedirected and re-directed across the spark plug 2 j for additionalignition at zone I₂, for example. In an embodiment, a flame from thespark plug ignition may propagate symmetrically across the combustionchamber C. Still further, the fuel injected by both injectors 12 a, 12a″ may generate tumbling fuel about the center axis of the cylinder 2 nwhich is believed by the inventors to promote higher turbulent kineticenergy which, in turn, promotes faster flame propagation and combustion.

The exemplary configuration shown in FIG. 11 includes a pre-chamber 2 qconfigured to receive a spark plug 2 jj (e.g., an M10 spark plug). Inthis embodiment the glow plug 2 m may be positioned on the opposite sideof the cylinder 2 n as the spark plug 2 jj but on the same side as theDI 12 a. Further, the spark plug 12 jj and pre-chamber 2 q may bealigned on opposite sides of the cylinder as the DI 12 a, all threecomponents being aligned along a central axis of the cylinder 2 n. Thisconfiguration may also include a pressure sensor 2 p (e.g., transducer)for monitoring the pressure within the combustion chamber C of thecylinder 2 n.

In an embodiment, fuel from the DI 12 a may be direct injected into thecombustion chamber C. As the fuel is injected it begins to vaporize. Inthis embodiment, the DI 12 a may be configured such that the fuel spray12 aa from one or more of its nozzles may be slightly directed towardsthe glow plug 2 m. In an embodiment, the so configured DI 12 a allowssome fuel (e.g., liquid fuel) within fuel spray 12 aa to land on a tipof the glow plug 2 m to provide ignition at zone I₁, for example, of thefuel by the glow plug 2 m during cold start conditions, for example. Thefuel from the DI 12 a may also travel towards, and be received into, thepre-chamber 2 q. In addition, heated air may be compressed by the actionof the opposed pistons (not shown in figures) and be received into thepre-chamber 2 q where the entrapped fuel and air may be ignited by thespark plug 2 jj at zone I₂, for example. In an embodiment, thepre-chamber 2 q may function as a secondary combustion chamber. Thecombustion of the fuel-air mixture within the pre-chamber 2 q maygenerate an increase in pressure that forces a heated, turbulent flow ofthe ignited fuel-air mixture (e.g., a heated jet-shaped flow) out of thenozzle 2 s of the pre-chamber 2 q towards the center of the main orprimary combustion chamber C of the cylinder 2 n. The heated, turbulentflow moves very fast to ignite the fuel-air mixture in the main chamberC when compared to the time it takes to ignite fuel in the combustionchambers in configuration that may incorporate flush mounted spark plugsor extra-long reach spark plugs. The resulting flame propagatessymmetrically across the combustion chamber C. In an embodiment. Stillfurther, the combination of a pre-chamber 2 q and embedded spark plug 2jj as shown in FIG. 11 is believed to reduce engine knocking in the mainchamber C and improve the knock margin while operating the combustionphasing closer to maximum brake torque (MBT) timing.

An exemplary engine that includes the configuration shown in FIG. 11 maybe referred to as a lean burn engine having a Lambda value of less than1.50, for example. This will enable the combustion process to operate athigher loads more consistently under lean burn conditions (Lambda<1.5).

Referring to FIG. 12 , there is shown yet another exemplary, enginecylinder configuration for the engine 2 a. This configuration includes apre-chamber 2 r configured to receive a DI 12 a and a spark plug 2 jj(e.g., an M10 spark plug). In this embodiment a glow plug 2 m may bepositioned on the opposite side of the cylinder 2 n from the spark plug2 jj and DI 12 a. Further, the spark plug 12 jj and pre-chamber 2 r maybe aligned along a central axis of the cylinder 2 n. In thisconfiguration the engine 2 a may also include a pressure sensor 2 p(e.g., transducer) for monitoring the pressure within the combustionchamber C of the cylinder 2 n.

In an embodiment, fuel from the DI 12 a may be direct injected into thepre-chamber 2 r. As the fuel is injected it begins to vaporize and isignited by the spark plug 2 jj within the pre-chamber 2 r at zone I₂,for example. In an embodiment, the pre-chamber 2 r may function as asecondary combustion chamber. The combustion of the fuel-air mixturewithin the pre-chamber 2 r may generate an increase in pressure thatcreates a heated, turbulent flow of the ignited fuel-air mixture (e.g.,a heated jet-shaped flow) which is forced out of the nozzle 2 ss of thepre-chamber 2 r towards the center of the main or primary combustionchamber C of the cylinder 2 n. The heated, turbulent flow ignites thefuel-air mixture in the main chamber C. The resulting flame propagatessymmetrically across the combustion chamber C. An exemplary engine thatincludes the configuration shown in FIG. 11 may be referred to as anultra-lean burn engine having a Lambda value of substantially less than1.50, for example, even less than the configuration in FIG. 11 becauseit is expected that less fuel may be needed to create combustion in themain chamber C. Accordingly, an engine 2 a that incorporates theconfiguration shown in FIG. 12 may provide an increase in fuelefficiency with lower emissions versus the other configurationsdescribed herein.

Similar to the configuration in FIG. 11 , the combination of apre-chamber 2 r and embedded spark plug 2 jj and DI 12 a in FIG. 12 isbelieved to reduce engine knocking in the main chamber C and improve theknock margin while operating the combustion phasing closer to maximumbrake torque (MBT) timing. Further, the configuration in FIG. 12 isbelieved by the inventors to result in improved brake thermal efficiencyand very low NOx emissions.

The components installed in each of the engine cylinder configurationsin FIG. 6A to 12 may be configured to be positioned within one or moresized openings in the cylinder 2 n. For example, in an embodiment aspark plug may be positioned within an opening that is sized for a glowplug, or vice-versa. To allow for such interchangeability of componentswithin different sized openings of the cylinder the inventors provideone or more adaptors that may be used to connect a spark plug or glowplug to a sized opening in a cylinder 2 n.

Referring now to FIGS. 13A to 13C there is depicted different views ofan exemplary adaptor 2 v. In an embodiment, the adaptor 2 v may have afirst opening in a first end a₁ whose diameter is sized to fit within anopening of the cylinder and a second opening in a second end a₂ whosediameter differs from the first opening and is sized to receive sparkplug or glow plug whose diameter is larger (or smaller) than the openingof the cylinder. Further, the exemplary adaptor 2 v may include threads2 y to threadably receive a correspondingly threaded spark plug,pressure transducer or glow plug, (e.g., those described elsewhereherein), for example. Still further, in one embodiment the end a₁ of theadaptor 2 v that is fit into an opening of the cylinder 2 n may comprisea compressible or deformable structure 2 x that is configurable todeform or compress in order to fit within the dimensions of one or moredifferent sized openings in the cylinder of an engine. Thus, the adaptor2 v can be said to fit with one or more different sized openings of acylinder of an engine, such as engine 2 a.

The claim language that follows below is incorporated herein byreference in expanded form, that is, hierarchically from broadest tonarrowest, with each possible combination indicated by the multipledependent claim references described as a unique standalone embodiment.

While benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments of the presentinvention. However, the benefits, advantages, solutions to problems, andany element(s) that may cause or result in such benefits, advantages, orsolutions, or cause such benefits, advantages, or solutions to becomemore pronounced are not to be construed as a critical, required, oressential feature or element of any or all the claims.

We claim:
 1. A compact and ruggedized system for producing powercomprising: a first generator; a second generator; an engine connectedto the first and second generators to provide energy to the first andsecond generators, the engine comprising one or more cylinders, whereeach cylinder comprises, a long-reach spark plug for ignition andcombustion close to a center of a combustion chamber of each cylinder, aglow plug, at least one direct injector configured to inject fueltowards the glow plug and into the combustion chamber.
 2. The system asin claim 1 wherein the first generator outputs at least 5 kWe of power.3. The system as in claim 1 further comprising a second direct injectorconfigured to inject fuel towards into the combustion chamber andtowards the spark plug, wherein the fuel injected by the at least oneinjector and the second injector generates tumbling fuel about a centeraxis of each cylinder.
 4. The system as in claim 1 wherein the enginecomprises an inwardly opposed piston engine.
 5. A compact and ruggedizedsystem for producing power comprising: a first generator; a secondgenerator; an engine connected to the first and second generators toprovide energy to the first and second generators, the engine comprisingone or more cylinders, where each cylinder comprises, at least onedirect injector configured to inject fuel towards a glow plug andtowards a pre-chamber, the pre-chamber configured to receive at leastone spark plug for igniting the fuel from the direct injector, and aglow plug for igniting fuel from the direct injector.
 6. The system asin claim 5 wherein the first generator is configured to output at least5 kWe of power.
 7. The system as in claim 5 wherein the engine comprisesan inwardly opposed piston engine.
 8. A compact and ruggedized systemfor producing power comprising: a first generator; a second generator;an engine connected to the first and second generators to provide energyto the first and second generators, the engine comprising one or morecylinders, where each cylinder comprises, a pre-chamber configured toreceive a direct injector configured to inject fuel into the pre-chamberand further configured to receive at least one spark plug for ignitingthe fuel from the direct injector in the pre-chamber and creating aheated turbulent flow out of the pre-chamber and into the combustionchamber of the cylinder to ignite fuel in the combustion chamber, and aglow plug for igniting fuel from the direct injector.
 9. The system asin claim 8 wherein the first generator is configured to output at least5 kWe of power.
 10. The system as in claim 8 wherein the enginecomprises an inwardly opposed piston engine.